The present invention relates to the field of devices used to sort and count spherical objects such as ball bearings.
The ability to efficiently and accurately sort by size spherical objects such as ball bearings is critical for various applications in various industries. For instance, for those industries that recycle and restore automobile parts, it may be necessary to sort ball bearings of various dimensions. Ball bearings are used in axles and other automotive parts, and are manufactured with various diameters that may differ by ten thousands of an inch. In order to efficiently recycle and reuse the ball bearings, it may be necessary to quickly and accurately sort the ball bearings by diameter. Frequently, it is useful not only to sort the ball bearings, but also to count the number of ball bearings of particular dimensions.
Machines used to sort spherical objects typically employ two rotating cylinders that are mounted such that their axes gradually diverge from each other. This arrangement creates a gap that gradually widens as the axes of the cylinders gradually diverge from one another. The two cylinders typically are mounted so that their diverging ends are lower than their tapered ends, so that objects to be sorted will gradually gravity feed down toward the diverging ends. Objects to be sorted are fed to the rotating cylinders at the tapered ends, where there is a minimal gap between them. As the objects feed toward the diverging ends, the objects drop through the gap at the point where the width of the gap exceeds the respective diameters of the objects. Receptacles are situated below the cylinders to collect the objects dropping through the gap created by the diverging cylinders at various widths of the gap.
For example, U.S. Pat. No. 4,172,527, issued to Bost, discloses a bearing sorting device that employs a pair of rotating cylinders and a diverging gap between the cylinders. The cylinders are mounted on an incline, each having a drive assembly connected to one end for rotating the cylinders in opposite directions. The bearings to be sorted are fed into the cylinders at the higher end, and the bearings gradually feed down the sorting gap until the width of the sorting gap is sufficient to permit the bearings to drop through into receptacles positioned accordingly to collect the sorted bearings. After the sorting operation has been completed, the bearings having the smallest diameter would be deposited in the first receptacle and the bearings have the largest diameter would be deposited in the last receptacle.
U.S. Pat. No. 4,767,010, issued to Bost, improves upon the above apparatus by increasing the accuracy of the sorting. The patent discloses a similar apparatus that includes flexible couplings between the drive shafts and supporting shafts of the cylinders. The flexible couplings decrease the effect of radial stresses on the sorting cylinders, thereby decreasing unwanted distortions in the sorting gap.
Although these machines are able to sort spherical objects to a fairly high degree of precision, they are not able to efficiently separate objects based on preset measurement ranges. Nor do these machines selectively reject objects that do not fall within preset measurement ranges. Nor do these machines count the number of objects sorted by preset measurement ranges. Thus, there is a need for a sorting device that can accurately and efficiently sort objects into preset measurements ranges and simultaneously count the sorted objects. There is also a need for a sorting device that is able to reject objects that do not fit into preset measurement ranges.
The present invention is a device for accurately and efficiently sorting spherical objects such as ball bearings. In its elemental form the device utilizes a hopper or some alternative feeder used to temporarily store and feed the objects to be sorted. The objects are gravity fed individually into an inclined measurement chute where they gravity feed past a tiny slot that is cut perpendicular to the path of the objects as they roll down the sorting chute. As each object passes the slot, the diameter of the object is measured by a laser micrometer. The laser micrometer determines the diameter of the object and sends a signal indicating the measured diameter to a programmable logic controller or some other computing means.
The programmable logic controller directs a servomotor to rotate a sorting chute to the appropriate position and then drop the object into a particular outfall chute. The object will travel through the outfall chute into a receptacle for that object""s particular diameter or range of diameter. The programmable logic controller maintains a running tally of the total number of objects sorted, as well as the number of each object measured at a particular diameter or range of diameter. If an object does not measure within one of the preset measurement ranges, the PLC directs the servomotor to place the ball in the outfall chute leading to a reject bin.
Because a laser micrometer is used to measure the diameter of each object, the precision of the ranges of diameters to be sorted can be extremely precise, essentially as precise as the laser micrometer utilized. Although the precision depends on the laser micrometer used, the best mode used by the inventor allows for objects to be sorted to forty millionths of an inch in diameter. This precision further allows for objects to be rejected if they have very small defects (such as foreign matter deposits) because the defects will cause distortion in the measured diameter. For instance, for particular applications utilizing ball bearings, very minor defects due to rust or carbon deposits may be significant, and the present invention allows for objects with these defects to be sorted out.
The present invention is efficient as well as accurate. The apparatus utilizes gravity to feed the spherical objects through a measurement chute and eventually into one of a plurality of receptacles situated below the measurement chute to receive the sorted objects.
It is an important aspect of this invention to provide a device for sorting spherical objects into preset measurement ranges at a high rate of speed.
It is a further aspect of the invention to provide a device whereby spherical objects can be sorted accurately into preset measurement ranges.
Another aspect of the invention is to provide a device for sorting objects to differences in diameter of eight millionths of an inch.
It is a further aspect of the invention to provide a device that will direct sorted objects to receptacles for collecting objects of a particular diameter or range of diameters.
It is another aspect of the invention to provide a device that will count the total number of objects sorted.
It is another aspect of the invention to provide a device that will count the number of objects sorted into each preset measurement range.
It is still another aspect of the invention to provide a device that will sort out objects that do not fall within a particular preset measurement range or ranges.
It is another aspect of the invention to provide a device that will sort spherical objects with a minimum amount of operator intervention or oversight.
It is another aspect of the invention to provide a device that will alert the operator when a preset number of objects of a given size has been sorted.